putting the car in neutral uses more gas then just taking your foot off the gas while in gear. in neutral your car is using gas to keep the needle at idle speed. if you are coasting in gear however, the injectors shut off completely and you use zero gas.

if you really want an easy way to control several levels of boost, get an EBC. set it to zero PSI when you dont want to boost. accelerating from a stop light is going to be a bitch though. just keeping your foot off the pedal when you can will save more while allowing the car to still be drivable. manual boost controls are more trouble then they are worth unless you have a larger turbo and need to control boost differently then with the N75.

 

Yes you could. It just needs to be any type of valve that you can turn open or closed, pretty much just like a water valve. it would be harder tyring to find one you can control from the driver seat since it would need to be electic and work off of a 12 volt source.


They do offer dual MBC's that allow you to control it while driving the car, its basicly just like a EBC but you manually set the 2 boost levels.





Problem is they are not cheap at $220-$250.

Turbosmart also makes a dual MBC that goes for $190.


Oh and I found this one from GFB for $107. http://www.ecrater.com/product.php?pid=1601258

 

haha, cool mike. What I was thinking was a long *** vaccum tube for the MBC or two position valve. Possible? And good to know ghost, thanks for presenting that in a helpful way. So even if I was cruising at like 40 down a hill with the revs at 2300 or 2500 or whatever it would be more efficient than neutral?

 

on the way home from work there is a 8% grade hill about 3/4 miles long that i throw the car into 4th gear and cruse down at 4k RPMs and dont burn a drop of gas and dont have to touch the brakes the whole way down. by the bottom of the hill the engine can cool off almost a whole tick mark on the temp gauge because there is no combustion happening. my air/fuel gauge is pegged at full lean the whole way.

 

You dont want to use really long vac lines for boost control, this is why the N75 valve hoses are very short and why EBC companies suggest using nothing over 18".

 

Yes because when you are off the throttle coasting in gear the wheels are actually keeping the engine spinning which is why you see rpms even though you are not touching the gas and as Ghost said the ecu completely shuts off the injectors so there is no fuel being sprayed into the cylinder.


BTW ghost your AFR is not pegged at full lean, its reading fresh air since that is what is being pumped thru the engine since there is no fuel being sprayed. So basically at that point your engine is just a huge air compressor.

 

Wow! Thats really cool and something I would have never guessed! Thanks gang. And its not hard on the engine to let it run downhill at 4K? I know its not redline, but still, the friction and everything?

 

running at high revs w/o throttle is a form of engine braking. its isnt really good for your engine, but isnt really bad for it either. as long as the wheels are spinning and the oil is being pumped, you're good. so basically speaking, there is very little friction cause you have oil in between the rings and cylinder walls.
if you were in nuetral at that time, the computer would send gas to the engine to keep the crank turning. since you're in gear going down that hill, the ecu doesnt send gas cause the engine is turning without the help of combustion. the only way to make it easier on your engine in that situation would be by shutting it off.

 

Thanks Redline!

 

Which should never be done seeing that you lose power steering and the brakes when you shut the motor off.